Treatment of reconstituted tobacco sheet



March ll, 1969 o. F. Llcls TREATMENT OF RECONSTITUTED TOBACCO SHEETFiled Sept. 1. 1966 United States Patent Oce 3,431,915 Patented Mar. 11,1969 3,431,915 TREATMENT F RECGNSTITUTED TOBACCO SHEET Osvalds F. Licis,Richmond, Va., assigner to Philip Morris Incorporated, New York, N.Y., acorporation of Virginia Filed Sept. 1, 1966, Ser. No. 576,676

U.S. Cl. 131-140 Int. Cl. A24b 9/00; A24c 5 06 This invention relates toa method for treating reconstituted tobacco sheet to provide that whenthe reconstituted tobacco sheet is shredded for use as a cigarettefiller, it has a filling capacity greater than that of ordinaryuntreated reconstituted tobacco sheet.

Various methods are known by means of which tobacco scraps and similartobacco residue evolved in the processing of tobacco products can beutilized in smoking articles. In general, the scraps and residue arereconstituted into a self-sustaining sheet, the reconstituted sheetthereafter being further processed and used as cigarette ller or cigarwrappers. The presnt invention provides a novel method by means of whichreconstituted tobacco sheet is contracted along bands extendinglongitudinally of the sheet and transversely spaced from each other.This is effected by subjecting the tobacco sheet along said bands tocompressive forces applied in directions parallel with the faces of thesheet and imparts non-uniform stress-strain properties thereto whichcause the tobacco shreds formed when the sheet is -shredded for use as acigarette filler, to curl and kink thereby increasing the bulk densityof the filler.

The treatment of the reconstituted tobacco sheet involves building uptherein a pattern of residual differential stresses which cause thesheet and consequently tobacco shreds formed therewith to curl and kinkin a fashion akin to that in which natural tobacco leaf becomes curledwhen it is steam dried in conventional tobacco processing methods. Thisinvolves producing an alternating arrangement of compacted andnon-compacted bands in the sheet and mechanically inducing thereinnon-uniform stressstrain characteristics. The reconstituted tobaccosheet may be treated with various forms of apparatus. However, apreferred embodiment of the apparatus comprises a pair of rollers one ofwhich is a heated smooth faced roller, and an endless, thick rubber beltwhich is provided on one side with an alternating arrangement of ribsand grooves to give it a discontinuous transverse surface. The endlessbelt is fed into the nip of the two rollers, with the belt traversing acourse partly around each, The tobacco sheet also is fed into the rollernip and against the discontinuous surfaced face of the endless belt sothat one face thereof engages the said belt face and the other face ofthe sheet engages with the smooth surface of the heated roller. Thearrangement is such that the endless belt traverses a course partlyaround each roller with the nip therebetween being at a point where thecourse of the sheet engaging face of the endless belt undergoes atransition from a convex travel on the unheated roller to a concavetravel on the other or heated roller. In this manner, the discontinuoussheet engaging face of the endless belt changes from a tensed to acompressed condition. The endless belt material is of such nature as tomaintain a strong frictional hold on the tobacco sheet so that thecompressed face of the belt applies a cornpression to the sheet atlongitudinally extending, transversely spaced areas of the sheet, thecompression being applied to the sheet in the direction of its faces andopposite to its direction of travel. Additionally, a compressive forceactin-g perpendicular to the run of the tobacco sheet is maintainedalong said areas by the tightened condition of the rubber belt therebypreventing any increase in thickness in the treated longitudinal bandsor areas of 6 Claims the tobacco sheet although the overall naturallength of said Ibands decreases. The action of the rollers and rubberbelt on the tobacco sheet thus is to rearrange the relative positioningsof and crowd together the tobacco constituents within the longitudinalbands, with the tobacco portions between said bands becoming creped.

Various other objects, features and advantages of the present inventionwill be made apparent by the description that follows and theillustrative examples depicted in the drawing. The invention accordinglycomprises the several steps and the relation of one or more such stepswith respect to each of the others, and the apparatus embodying featuresof construction, combinations of elements and arrangements of partswhich are adapted to effect such steps, all as exemplified in thefollowing detailed description and the scope of the invention will beindicated in the claims.

In the accompanying drawings:

FIGURE l is a side elevational View of a preferred embodiment of theapparatus with which reconstituted tobacco sheet may be treatedaccording to the principles of the present invention.

FIGURE 2 is a transverse sectional view through the flexible belt usedin the apparatus of FIGURE l.

FIGURE 3 is a partial longitudinal plan view of a reconstituted tobaccosheet treated with the apparatus of FIGURE 1 in accordance with thepresent invention showing the alternate arrangement of compacted andnoncompacted bands therein which produce non-uniform residual stressesand strains in the tobacco sheet to thereby increase its lling capacitywhen it is used as a cigarette filler.

FIGURE 4 is similar to FIGURE 3 except that the alternate compacted andnon-compacted bands in the tobacco sheet are directed angularly of thelongitudinal axis of the sheet as occurs when the ribs and grooves onthe endless belt are arranged to extend at an angle to the major axisthereof.

FIGURE 5 is a fragmentary plan view on enlarged scale of a section oftreated reconstituted tobacco sheet showing the planar contours producedtherein by the method of the present invention.

FIGURE 6 is a sectional view as taken along line VI- VI in FIGURE 5.

The present invention is concerned with the treatment of reconstitutedtobacco sheet, i.e., one which is made from tobacco stems and othertobacco residue, the sheet being formed by casting it in a Fourdrinierapparatus in the same general manner employed in paper making. Thepresent invention contemplates that the wet sheet of tobacco on leavingthe Fourdrinier apparatus, that is, on being removed from the wireforming carrier will be subjected to some drying. This. may be carriedout by means of suction boxes, Yankee drier unit, or other conventionaldrying equipment and is intended to reduce the water content of the wettobacco sheet to a range of between 12% and 25% by weight lbutpreferably about 15%. The tobacco sheet is then directed into the rollerapparatus shown in FIGURE l. The apparatus comprises a pair of drivenrollers 11 and 12, the roller 12 being a heated drum which has a smoothouter surface that will oier low frictional resistance to the movementof the tobacco sheet 10 thereon when the latter is brought into contactwith it in the manner to be described later on in the specication.Intermediate the two rollers 11, 12 there passes a continuous beltmember 14, the outer surface 16 of which is of a contractible characterand to that end, the belt member 14 is preferably made of rubber. Theapparatus also includes an additional roller 17 -around which the beltmember .14 passes with the roller 17 ybeing spaced suicient distancefrom roller drum 12 to provide a ing of the invention.

straight belt run transfer from the roller drum 12 to roller 17. A guideroller 18 is also provided. The outer surface or face 16 of the belt,i.e., the tobacco sheet engaging face is discontinuous in a transversedirection as shown in FIGURE 2 having extending thereon a plurality oftransversely spaced, longitudinally extending ribs 20, with grooves 21extending between adjacent ribs. In a preferred form of the belt, thewidth of the ribs 20 should be in a range between 1/10 of an inch and 1(one) inch, the preferred width being between 1A and 3/8 of an inch. Itwas found that to achieve an improvement in the lter characteristics ofreconstituted tobacco sheet, the application of the compressive forcesthereto has to be effected along relatively narrow bands or areas of thesheet. Hence, the use of rib widths in the range above. The grooves 21should be at least equal to the widths of the ribs although they can bemade with a somewhat larger dimension without producing change in theteach- The arrangement of the rollers 11 and 12 is such that the face 16of the belt .14 (which is comprised of the at surfaces of the respectiveribs 20 and which contacts the tobacco sheet) undergoes a transitionfrom a convex run on the drum 11 to a concave run on heated drum 12, thebelt face 16 shortening or contracting as it undergoes this transition.As .a consequence, the tobacco sheet feeding intermediate the outer faceof the belt 14 and the smooth outer face of heated drum 12 is grippedtightly by the transversely discontinuous belt face and responsive tothe contraction of the latter, is subjected to compressive forcesexerted parallel to the faces of the tobacco sheet and counter to thedirection of the sheet run thereby distorting and exing the tobaccoconstituents in the reconstituted sheet along longitudinal directedbands corresponding to the location of the ribs 20 on the belt 14. Itshould be understood that the phenomenon of distorting and flexing thetobacco constitutents is in effect a rearrangement of the relativepositions of the pectins, hemicelluloses, galacturonic acids and otherconstituents which comprise reconstituted tobaco, the constituents beingpushed or crowded together in a ydirection opposite to the sheet travelwith resulting shortening of the natural length of the sheet. It isbelieved that little or no actual geometric distortion of the tobaccoconstituents occurs as reconstituted tobacco sheet constituents rarelyhave length/width ratios greater than 1:1 and as such -are not amenableto physical distortion and changes in geometric configuration in thesame manner as fibrous materials, as for example, paper fibers havinglength/width ratios in excess of 5:1.

As seen in FIGURE 3, the treated tobacco sheet has Van alternatingarrangement of compacted bands 40 and non-compacted vbands 41corresponding respectively to the rib-groove arrangement on the beltmember 14. During the course of treating the tobacco sheet, theprimitive lengths of the compacted band portions 40 are progressivelyshortened without any increase in the thickness thereof, this beingprevented by the action of belt 14 in holding the sheet in tight contactwith the roller drum 12 and applying a compressive force normal to thedirection of travel of the tobacco sheet. The non-compacted bands 41 onthe other hand are not subjected to shortening of their primitivelengths. Instead, they assume a randomly patterned creped conditioncaused by the shortening of the two compacted band portions 40 adjacenteach non-compacted band 41. This condition is shown with greater clarityin FIGURE 5 wherein it will be noted the compacted bands 40b are smoothfaced at both sides of the sheet and the non-compacted bands 41b have anundulating contour 43 characteristic of creped sheet.

The effect of compacting the tobacco sheet only along longitudinallydirected, transversely spaced bands is to mechanicaly induce stressesand strains in the sheet and impact varying dimensional characteristicsthereto. In other words, the reconstituted sheet on being treated asdescribed assumes a non-uniform modulus of elasticity. This will beapparent by referring to FIGURE 6. The compacted bands 40b which havebeen stressed are of flat section. The non-compacted bands 41b howeverexhibit the randomly arranged undulating segments 46. Thus when thesheet is shredded along shear planes X-Y for filter purposes, the shredis comprised of a stressed segment 47 represented by the compacted bandportion of the shred and a relatively non-stressed segment 46. Thestress `differential within the respective segments `of each shredcauses it to assume a curl or kink. A reconstituted tobacco sheettreated uniformly throughout its width instead of in an alternatebanding arrangement will on the other hand, possess a uniform modulus ofelasticity and shreds formed therefrom lacking a stress differentialwill not curl -or kink. The difference is of consequence when therespective sheets are used as .a cigarette filler as will appear.

When ordinary untreated reconstituted tobacco sheet is shredded for useas a cigarette filler, the shreds produced for the most part lay fiatand occupy less space than natural leaf tobacco shreds. Natural tobaccoleaf on the other hand, is curly and possesses a stress and straintherein imparted by steam drying during leaf processing so the tobacco-shreds kink or twist when the leaf is shredded, thus increasing itsbulk density or filling capacity. The reconstituted tobacco sheettreated as described above, i.e., one compacted in alternate bandsextending longitudinally of the sheet does not suffer the limitation oflaying flat during `cutting so that the shreds possess a kink or curlakin to that of natural tobacco leaf giving the ller increased bulkdensity.

Further understanding of the invention will appear from the followingexamples.

Example 1 A reconstituted tobacco sheet which was cast in a Fourdrinierapparatus and dried to a water content of about 15% by weight of Waterwas treated as previously described on apparatus as shown in FIGURE 1and having a rubber belt. The treated sheet was then shredded to serveas cigarette filler.

An untreated reconstituted tobacco sheet also was shredded providing afiller with which cigarettes serving as a control were prepared.

During the shredding, the reconstituted tobacco sheet treated accordingto the present invention had a non-uniformity of shred (a curl or kink)and the curled and intertwined shreds were easily handled when makingcigarettes. 'llhe untreated reconstituted tobacco sheet made flat shredswhich were more difficult to handle.

Control and experimental cigarettes were then made from the respectivetreated and untreated tobacco sheet fillers to provide 'data on thelling power of each. Since filling power is di'icult to define anddetermine, it was necessary to select varialbles most likely to give acorrelation with 'filling power. Accordingly, the cigarettes were madeat a constant resistance-to-draw (RTD expressed in inches of water). TheRTD of both the control and the experimental cigarettes was 2.2-2.6inches yof water. The cigarettes were mm. long and had a circumferenceof 25.2 mm. The weight of the cigarettes made from the treated iller was0.956 gram/cigt. From four ounces of the treated filler, 119 cigaretteswere prepared. From four ounces of the control, 117 cigarettes wereprepared.

Since the RTD o-f the cigarettes remained constant and since morecigarettes were made from the four ounces of the test filler, it wasevident that the treatment of the reconstituted tobacco sheet accordingto the present invention increased the bulk density of the ller and itwas concluded that the treated tobacco sheet has a greater filling powerthan the untreated control sheet.

Example 2 Control and test cigarettes were prepared as described inExample l with the RTD kept constant at 2.2-2.6 lnches of water. Thecigarettes made were mm. long and had a circumference of 25.2 mm. Thetest cigarettes were filled with 1.144 grams/cigt. and the control with1.216 grams/cigt.

From four ounces of the treated filler, 99 cigarettes were made.Ninety-four (94) control cigarettes were made from the four ounces ofuntreated filler. Thus, approximately 5% more cigarettes were made withthe treated filler than with an equal weight of the untreated filler.

Example 3 In a similar experiment to determine the filling power of testand experimental cigarettes, the cigarettes were kept at a constantWeight. The cigarettes differed from those described in Examples 1 and 2as follows: the cigarettes were made to a constant weight of 103-107cigarettes per 4 ounces of rfiller; they had a length of 65 mm. and acircumference of 25.2 mm. The control cigarettes were made of a blend ofpredominantly natural leaf filler and shredded filler from anuntreatedreconstituted tobacco sheet. Comparisons of the filling power of testcigarettes and the control were made by determining their RTD, a measureof bulk density of the cigarettes. The treated cigarettes h'ad an RTD of3.0; the control ihad an RTD of 2.9 showing that the treated cigaretteswere more tightly packed than was the control. This indicated anincreased filling power.

Example 4 Test cigarette filler was prepared as ydescribed in Example 1.T-he control cigarettes had the same filler as the control in Example 3.Test and contr-ol cigarettes were made to a constant RTD of 2.0-2.2inches of water. The cigarettes made were 65 mm. long and had acircumference of 25.2 From 4 ounces of the treated ller, 119 cigaretteswere made. From 4 ounces of the blend used as the control, 115cigarettes were made. The increase in the number of cigarettes preparedfrom the treated cigarettes indicated that the filling power of thetreated filler was greater than that of the blended ller.

It will be understood from the foregoing description that the presentinvention requires compacting or contracting a reconstituted tobaccosheet in narrow longitudinally directed, transversely spaced bands toachieve an improvement in the filling properties of the sheet when it isused as a cigarette filler. While the compaction of the sheet is carriedout in an effective manner with the apparatus of FIGURE 1, it will beIapparent that other devices can be employed to produce the same effect.For example, a roller set having a speed differential therebetween andemploying a discontinuous surface on one of the rollers could also beused. Moreover, the construction of belt member 14 can be modified toprovide it with ribs extending angularly of the longitudinal axisthereof so las to produce a compacted band 40a-non-compacted band 41aalternating arrangement pattern such as that shown in FIGURE 4.

The present invention provides an effective manner with which thefilling properties of reconstituted tobacco sheet can be improved whenit is used as a cigarette filler. It is possible to produce a more densecigarette from a given weight of treated reconstituted tobacco sheetthan is possible when using an equal weight of untreated sheet. Not onlyis the bulk density of reconstituted tobacco sheet improved when it istreated according to the present invention but better resistance-to-drawqualities, as shown by Example 3, as well as firmer packing of thecigarettes made therewith are achieved.

What is claimed is:

1. A process for treating reconstituted tobacco sheet to increase itsfilling capacity when it is used as cigarette filler which comprises,

compacting said sheet in transversely spaced flat bands extendinglongitudinally of said sheet to shorten the natural length of saidcompacted bands, leaving between succeeding compacted bands uncompactedbands of reconstituted tobacco the natural lengths of which aresubstantially unchanged,

the compacting of said sheet being effected by subjecting it while it isadvancing in a longitudinal course, to compressive forces appliedparallel to the sheet faces and counter to the advance thereof so as torearrange the relative positioning of the reconstituted tobaccoconstituents within said compacted bands and therewith establishresidual differenti-al stresses between the renconstituted tobacco ineach cornpacted band and reconstituted tobacco in the uncompacted bandsadjacent thereto,

while simultaneously applying compressive force to said compacted bandsin a direction normal to the faces thereof to prevent an increase in thethickness of said compacted bands as the natural lengths thereof areshortened, and

thereafter shredding said sheet into shreds each comprised of at least asegment from one of said compacted bands and a segment from anuncompacted band so that the stress differential existing between thecompacted band segment and uncompacted band segment cause said shred tocurl and kink.

2. The process of claim 1 wherein the sheet of reconstituted tobacco issubjected to the application of said compressive forces and counter tothe advance thereof normal to the faces of said compacted bands while itis in a wet state containing water in a range of between 12% to 25% byweight of the sheet.

3. The process of claim 2 wherein the sheet is subjected to theapplication of said compressive forces while it is in a wet statecontaining substantially 14% by weight of water.

4. The process of claim 1 wherein the width of the transversely spacedbands at which said compressive forces are applied is in a range between1/10 inch to l (one) inch, and the spacing between succeeding bands isat least equal to the width of said bands.

5'. The process of claim 4 wherein the width of the transversely spacedbands at which said compressive forces are applied is in a range between1A inch to 1%; inch.

6. The process of claim 1 wherein the reconstituted tobacco sheet iscom-pacted by advancing it in a wet state in a longitudinal directionand between and in contact with the juxtaposed surfaces of two movingbodies, one of which is heated, the surface of the other of said bodiesbeing discontinuous in a direction lateral to the advance of the sheetand being smooth and contractible and offering greater frictionalresistance to the movement of the sheet thereon than that offered fbythe surface of said heated body, the discontinuous surface of said otherbody being contracted in a direction counter to the `advance of saidsheet to apply compressive forces parallel to the faces of said sheetfor shortening the natural length of the reconstituted tobacco sheetcontacted by said continuous surface, the compressive force appliednormal to the faces of the sheet being applied by maintaining a fixedspacing of the juxtaposed surfaces of said two moving bodies.

References Cited UNITED STATES PATENTS 3,299,895 1/ 1967 Dearsley 131-20MELVIN D. REIN, Primary Examiner.

U.S. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,431,915 March ll, 1969 Osvalds F. Licis It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as shown below:

Column 2, line 14, "arrangements" should read arrangement Column 3, line73, "impact" should read impart Column 6, line 35, "l4% should read 15%Signed and sealed this 31st day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents

1. A PROCESS FOR TREATING RECONSTITUTED TOBACCO SHEET TO INCREASE ITSFILLING CAPACITY WHEN IT IS USED AS CIGARETTE FILLER WHICH COMPRISES,COMPACTING SAID SHEET IN TRANSVERSELY SPACED FLAT BANDS EXTENDINGLONGITUDINALLY OF SAID SHEET TO SHORTEN THE NATURAL LENGTH OF SAIDCOMPATED BANDS, LEAVING BETWEEN SUCCEEDING COMPACTED BANDS UNCOMPACTEDBANDS OF RECONSTITUTED TOBACCO THE NATURAL LENGTHS OF WHICH ARESUBSTANTIALLY UNCHANGED, THE COMPACTING OF SAID SHEET BEING EFFECTED BYSUBJECTING IT WHILE IT IS ADVANCING IN A LONGITUDINAL COURSE, TOCOMPRESSIVE FORCES APPLIED PARALLEL TO THE SHEET FACES AND COUNTER TOTHE ADVANCE THEREOF SO AS TO REARRANGE THE RELATIVE POSITIONING OF THERECONSTITUTED TOBACCO CONSTITUENTS WITHIN SAID COMPACTED BANDS ANDTHEREWITH ESTABLISH RESIDUAL DIFFERENTIAL STRESSES BETWEEN THERENCONSTITUTED TOBACCO IN EACH COMPACTED BAND AND RECONSTITUTED TOBACCOIN THE UNCOMPACTED BANDS ADJACENT THERETO, WHILE SIMULTANEOUSLY APPLYINGCOMPRESSIVE FORCE TO SAID COMPACTED BANDS IN A DIRECTION NORMAL TO THEFACES THEREOF TO PREVENT AN INCREASE IN THE THICKNESS OF SAID COMPACTEDBANDS AS THE NATURAL LENGTHS THEREOF ARE SHORTENED, AND THEREAFTERSHREDDING SAID SHEET INTO SHREDS EACH COMPRISED OF AT LEAST A SEGMENTFROM ONE OF SAID COMPACTED BANDS AND A SEGMENT FROM AN UNCOMPACTED BANDSO THAT THE STRESS DIFFERENTIAL EXISTING BETWEEN THE COMPACTED BANDSEGMENT AND UNCOMPATED BAND SEGMENT CAUSE SAID SHRED TO CURL AND KINK.